S2 E39 3D Modelling a Railway Carriage Part 1 

Thanks Peter. I'm a Jack of all trades - but master of none! :) All the best, James

Thank you Matt, I'm pleased you found the video interesting. Thanks also for the constructive feedback, I thought the background music might soften my droning-on. I'll think again next time. :) Thanks for watching, James

Thank you Paul, part 2 is now up - there may even be a part 3 on the way, just as soon as I clear-up a couple of other bits and bobs. Thanks for watching, James

Hi Phil, I totally agree with your logic here. However, if I'm drawing something for a specific model scale then it makes sense to me to base my drawing in units to which work well with the materials I intend to use. For example, I'm currently drawing up the artwork for a locomotive chassis which will be etched. The starting point being the thickness of the material I intend to use. That being the case it works for me to use that unit as the basis for the drawing, which is especially helpful when dealing with things like slots and tabs. In essence the same though process as you describe, just with inverted logic. Simply scaling from full-size can produce odd-sizes. Not a problem with a 3d print, but with fabricated parts, one often has to select from stock material sizes, with inevitable rounding-up or down errors, which can lead to 'stack-up' errors in a fabrication. If I'm drawing something as a digital model only then I always use the parent units, often full-size imperial. Thanks for watching, James

Glad you liked it, and I could certainly do with a rest. :)

Cheers Mike, give it a go. I think the 2d part is the hardest. Once a 2d profile has been created, the subsequent extrusion, cut or revolve is straightforward. Good luck, James

Cheers! I'm loving your new logo by the way, and your recent posts. Keep it up! :)

Thanks Keith. I like to use various bits of software to keep my hand-in, but essentially they are all the same. I'm looking forward to starting on a Thumper soon. The next episode is now up. I hope you find it useful. All the best, James

Thank you Malcolm, you're tight it's not easy to produce a video like this, not is it an easy watch so thank you for your patience. As for laser cutters, if it's your first I'd now recommend a diode laser over Co2 for easy of use, although a Co2 laser is more versatile. I would try to go for something like 20w as a minimum as a good compromise between speed and cutting power. I'm certain that any 5w laser would do most of what you need, but slightly more power makes for a more pleasant quality of life in use. I'm presently reviewing a 60W diode laser which is a beast, it's absolutely amazing, but realistically quite unnecessary for model making work. Indeed, it may even be a little dangerous. :) As for glues, I tend to use CA glue for just about everything as I'm impatient, otherwise its quality PVA for most other jobs and school-type PVA to glue plywood sleepers down. Why school-type glue? Well, if something goes down in the wrong place it is easy to spray with water, cover with cling-film overnight and lift/reposition with very little damage. :) Thanks for watching, James

I think it's a matter of personal preference really. When I'm making a model I like to use the model scale and dimensions as it's handy to be able to 'visualise' the key dimensions dimensions that I'm working with. For example, I know the axles will be made from 2mm diameter bar, so the design of the bearings and details inside the axleboxes will be based around this 2mm dimension. The same applies for things like coupling hooks and handrail wire, etc. for which I will be using parts and materials with specific dimensions. That being the case, it makes sense (to me at least) to scale the entire model and use model dimensions throughout. If this were a generic model, which I anticipated reproducing in a variety of scales, then I would probably draw full-size and scale at the point of printing. It is also possible to create a table of key dimensions, and set the drawing to 'read' these when creating a part. This is a useful technique when planning to produce an item in different scales. For example, we could create a data entry for 'axle diameter', with separate columns for 2mm,3mm,4mm & 7mm scales etc. with a different diameter for each. We can then reference the drawing to the relevant piece of data in the table depending upon what we require. Imagine something like a locomotive wheel, if we tabulate all the key dimensions and parameters; diameter, no of spokes, crank pin position, etc. then we can write a formula to produce, (for example), a 5'6" diameter wheel with an S7 tyre profile with 16 spokes, crank in-line to suit a 24" piston stroke. In practice, it's a little more involved than that - but that's the basic process of parametric modelling. Usually though, I just sit at my computer and doodle to pass time - hence I've a hard-drive full of quite interesting stuff - most of which I've forgotten I've drawn. :) Thanks for watching, James